Gaseous discharge device



April 1953 F. W. STUTSMAN 2,636,144

GASEOUS DISCHARGE. DEVICE Filed Feb. 3, 1951 Patented Apr. 21, 1953GASEOUS DISCHARGE DEVICE Paul W. Stutsman, Needham, Mass., assignor toRaytheon Manufacturing Company, Newton, Mass., a corporation of DelawareApplication February 3, 1951, Serial No. 209,220

Claims.

This invention relates to gaseous-electron-discharge devices containingelectrodes comprising wires of extremely small diameter.

This invention discloses the discovery that, when an electrodecomprising an extremely fine wire having a diameter on the order of .001of an inch is positioned adjacent a source of electrons, such as anindirectly-heated cathode in a gaseous medium, and a positive voltage isapplied to said electrode with respect to said electron source,electrons attracted from the source toward the electrodes will collidewith gas molecules producing ions and electrons greatly in excess ofthat required to maintain a discharge between the electron source andthe fine wire electrode.

As a result, if an anode having a substantial surface is placed in thevicinity of the discharge between the electron source and the fine wireelectrode, for example, by making the anode in the form of a cylindersurrounding both the electron source and the fine wire electrode, asubstantia1 quantity of electrons will flow from the electron source totheanode even with no potential difierence between the anode and theelectron source.

Indeed, it has been found that substantial quantities of electrons willflow from the electron source to the anode when the anode is negativewith respect to the electron source, the magnitude of this electron flowbeing a function of the positive voltage applied to th thin wireelectrode and the amount of the negative voltage applied to the anode.Because of this phenomenon, it is possible to use agaseous-electron-discharge device of this type as a voltage-transformingdevice, wherein relatively high voltage at low current may be convertedto low voltage at relatively high current.

It has further been discovered that, if a particular potential isapplied between the thin wire electrode and the electron source, and apositive potential is applied to the anode, the drop between the anodeand the electron source will remain substantially constant over arelatively wide range of anode currents, thus demonstrating that thedevice has the characteristics which will enable it to operate as agaseous-voltage-regulating tube, and having the advantage that thedesired regulating voltage may be adjusted by adjusting the potentialapplied to the thin wire electrode, and also that the regulated voltagedeveloped between the cathode and anode of the device will beconsiderably below the operating voltages obtainable by other types ofgaseous- 2 tube regulators. For example, the regulated voltage may be onthe order of ten volts or less.

Further, since the voltage developed between the cathode and anode maybe varied as a function of the thin wire electrode voltage, the deviceexhibits the properties of an amplifier, and may be so used, if desired.

It has been discovered that a particularly useful gaseous medium forthis discharge device comprises a mixture containing substantiallyninety per cent krypton and ten per cent xenon at a total pressure ofone hundred microns of mercury.

Other and further objects and advantages of this invention will beapparent as the description thereof progresses, reference being had tothe accompanying drawing, wherein:

Fig. 1 illustrates a longitudinal, cross-sectional view of agaseous-electron-discharge device embodying this invention, taken alongline l-l of Fig. 2;

Fig. 2 illustrates a transverse, cross-sectional view of the deviceshown in Fig. 1, taken along line 2-2 of Fig. 1; and

Fig. 3 illustrates a graph showing operational characteristics of thedevice illustrated in Figs. 1 and 2.

Referring now to Figs. 1 and 2, there is shown an envelope H) which maybe, for example, of glass, said envelope being sealed to a glass pressII at the bottom thereof. Extending upwardly from the glass press I l isa plurality of supports which are attached to various elements of thedischarge device. A support I2 is attached to a cathode I3 which isshown here as a cylinder coated with electron-emissive material I4, andheated by a heater wire I 6 connected to the support and lead-ins l1 andI8, respectively, said lead-in members extending through the glass pressII to provide electrical contacts external to the envelope [0.

Surrounding cathode l3 and spaced therefrom is an anode cylinder l9which is coaxial with the cathode l3. Cylinder 19 is supported by a pairof side rods 20 and 2|, respectively, whose lower ends are imbedded inthe glass press ll. Upper and lower mica spacers 22 and 23,respectively, cover the ends of anode cylinder l9 and extend slightlyover the ends of the cathode cylinder [3, said mica spacers extendingsubstantially out to the walls of envelope l0. Rods 20 and 2| extendthrough mica spacers 22 and 23, thereby insur- I 3 24 extends betweenthe mica spacers 22 and 23 parallel to the cathode cylinder 13 at apoint approximately a half wave between the cathode cylinder [3 and theanode cylinder l9. At its lower end Wire electrode 24 is attached to aleadin support 25, and at its upper end wire electrode 24 is attached toa spring support 26 which, in turn, is .attachedc. asby Welding, toarod2'1,v one. end of which is imbedded in glass presswl I and extendsupward through the mica spacers 22 and 23 outside the anode cylinder I9.

Referring now to Fig. 3, there is shown a graph illustrating theoperation of the-gaseous-d is charge device of Figs. 1 andAlongthe-axis. of ordinates is plotted anode. voltagerelative to..-

the cathode I3, while along the axis'of aabscissas is plotted anodecurrent in milliamperes. Curve 28 illustrates the characteristic"of'the"device Which would allow its use as a step-downvoltage transformer. Asisishown by point 29, at zero. current, .theanode voltage is minusbetween one and ftwo'.voltspvvhen one hundred and. ten voltsare applied.between the auxiliary wire electrode. and. the. cathode, ,saidjauxiliary wire. elec. trode." voltage. being... labeled egv on the.graph,.,of. Fig; 3. With .eg. remainingconstant at one. hundred and tenvolts, thebanode voltage. becomes less-negative the anodecurrentincreases. from zero luntil at.,a pproximately thirty milliamperes 0t;current-,. the. anode. voltage. is approximately 0 zero, asiis.indicated...by ,point. 3%... Thus, if one hundred.andtensvoltswareapplied .to the. auxiliary electrode, and a current ofarounclfifteen milliamperes.isaallowed. .to .ilow. inthe. anodecathode.circuit, a..negative,voltageon the. order of. one; voltrwill. appear.between-the anode and the cathode, saidcsvoltage.bein available, forexample, for... biasing-l other. electron-discharge tubesor..ioresuppl-ying, a..heatei:. current to. other electron-discharge tubes;

As is shown in this graph by Way of example; with the auxiliaryelectrode held constant, for example; at.- one hundredand ten-.:volts-,;the. plate voltage rises rapidly between currents. oiiorty fifthmil-liamperes'. QfwPlEttfi current +untilg-the anode. voltageqreacheea:voltage. on. the; order. .of eight or ten volts, at which time thevoltage; again levelsrofi asthe.dischargevdevice approaches.conditionsxo iarcidischarg-ev If a vo1tage,-.-.oi,-.for example.;.volts ;is to thee electrode; anode-cathode voltage dropswill remain-.suhstantially .cons,tantat approximately one-half. volt fonarcurrentrange-offrom twenty to =f1orty:-milliamperes,; thus providing acharacteristic which may be used to produce ;;aclowvoltageLregulatedoutnut acrossztheanode-cathode circuit of the.devic:e;.;said; anode: being. connected; for example, to; ahigherwoltage; source through a dropping resistom:inxaccordance:'witlr..:we1bi knownvoltagez regulator: practice." This is illus; tratedby a curve 3! in Fig. 3.

If. the voltagev applied to theauxiliary electrode is zero,- the.anodewathodei voltage .dropmvili'b'e on the orderof'eiglit volts,Wl1i1e;ior variousivoltrzages applied to. theauxiliary61Gctr02d63b6tlll68ll zero and. fifty-*volt various curveschaving subsstantially c onstantyoltages in. the: currentirange betwceir twentyand:'fortwmilliamperes: may be obtainedr- These; curves are. shown, forexample; by the dotted li nes 3:2? aid 'curves substantialiy matching.with: curve. 282% kWh-err: anode :currents exceed between. forty'landiiity miiliamperes.c.

It; ShQl'lld,19BfHOtSBditihfll'ttthE efficiency; of genere? ation'ofrtheexccsspositiveyions by:.;therthirr ,wire electrode isidependentomthe;diameter of the thin diameters as high as .004 of aninch.

wire. For optimum results, the diameter of the thin wire should be muchless than the length of the mean free electron path, for example, onetenth the length thereof. In addition, the gas pressure must besufficient to produce enough ions to substantially neutralize theelectron space charge of the device. While the particular gaseous'medium :disciosed herein comprised krypton and xenon' at a pressure oi:one hundred. microns of mercury, other gases, such as mercury or helium,could be used, and the pressure of the gaseous medium could be as low asfifty microns of'mercury. At the low pressure of fifty microns, resultsmay be obtained with thin wire electrode When higher-pressures are used,for example, pressures of greater than one thousand microns of mercury,the'thilrwire electrode diameter should be very small-,iiorexample, lessthan .001 of an inch.

This completes the description of the particular embodiment of. theinvention illustrated herein. However,v many modifications thereof. willbe apparent to persons skilled inthe. art without departingiromthe-spirit and scope of. this invention For example, the auxiliary wire.electrode hasacurrent voltage charaoteristicwhich prevents an are fromoccurringbetween the electron source: and. thcauxili-ary electrode. Thisportion 011 the tube could lee-used alone as a resistance having. apositive voltage currentcharacteristic throughout its entire range of,appliedvoltages. In. addition, the particular configuration of theelectrodes and their support. means'is-by way of illustration only.Accordingly. it 'is desired that this. invention be not limited by-the.particular details of the embodiment described herein, except as definedby the-appended claims What is claimed-is A, gaseous-eiectron.-dischargedevice com.- prising an envelope containing a gaseous medium, asource ofelectrons, an anode,.and an auxiliary electrode, saidelectrodecomprisinga Wire having a diameteron the. order of .001. of an-inch.

2rd gaseouseeleotron-dmcharge device compri-singanenvelope containing agaseous medium, a source of free electrons, and an electrodesp-aced fromsaid: sour c; said electrode comprisinga wire having a diameter on theorder of 1001.01" an inch.

3.= A. gaseous-electron-discharge device comprising-anenvelopecontainingaaseous medium, acathode of.theaheated type, ands-anelectrode spacedirom. said; cathode, said electrode comprisingea wire.having. a diameter on the-order 013.661 Oran-inch.

4. a A: .gaseous-electronrdischarge device comprisingzanenvelopecontaining a gaseous medium, a cathode; an anode, and anauxiliary electrode, said electrode comprising. a=-wire having adiameter on the order or" .001 of an inch.

5: A gaseouselectron-discharge:z device 1,. comprising: anenvelopecontaining a gaseousmedium, am indirectly heated cathode;- an.anode, audan auxiliary electrodasa-id electrode comprising aWirewhaving. a diameter on the order of: aOO-L 0t anyinoh'.

6. A: gaseous-electrondischarge1 device com.- prisinganxenvelopecontaining'a gase'ousmedium; a-cathodeyan anode coaxialwithsaid cathode, and an: auxiliary electrode; said. electrodecomprisinga. wire" having a diameter on: theorder of .001 ofcan inch..-

7-. .A gaseous-electron-discharge device. comprising an envelopecontaining a gaseousmedium, asourceofelectrons, saidmedium comprising aninert-gas,: and. an electrode spaced: from said source, said electrodecomprising a wire having a diameter on the order of .001 of an inch.

8. A gaseous-electron-discharge device comprising an envelope containinga gaseous medium, a source of electrons, said medium comprising an inertgas at a pressure on the order of one hundred microns of mercury, and anelectrode spaced from said source, said electrode comprising a wirehaving a diameter on the order of .001 of an inch.

9. A gaseous-electron-discharge device comprising an envelope containinga gaseous medium, a source of electrons, said medium comprising kryptonand xenon at a pressure on the order of one hundred microns of mercury,and an electrode spaced from said source, said electrode comprising awire having a diameter on the order of .001 of an inch.

10. A gaseous-electron-discharge device, an envelope containing agaseous medium at a pressure on the order of one hundred microns ofmercury, a source of electrons, and an electrode spaced from saidsource, said electrode having a diameter substantially less than themean free electron path in said medium.

PAUL W. STUTSMAN.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,027,175 Kallenbach Jan. 7, 1936 2,340,799 Depp Feb. 1, 19442,351,254 Elmendorf June 13, 1944 2,459,579 Noel June 18, 1949

